1. Field of the Invention
The invention relates to a process for inscription of a sheet-like adhesive system of a polymer, preferably on the side averted from the adhesive side, with information, e.g. indications to identify the system as such or the object to which the system is to be adhered.
2. Description of the Related Art
There are many different types of sheet-like adhesive systems of a polymer, such as:                adhesive films, e.g. (possibly transparent) adhesive films for identification marking of switchboards and technical appliances,        technical adhesive strips or tapes,        fixing plasters (e.g. for fixation of bandages) for application on the skin,        wound plasters with wound dressings,        plasters with active agents such as antirheumatic plasters for topical application of active agents to the skin,        plasters with active agents for system application of active agents onto and through the skin, so-called transdermal therapeutic system (TTSs),        plant protection plasters comprising active agents for application of plant protection agents.        
With sheet-like adhesive systems there is a need to apply information relating, for example, to their properties, their use, their intolerances or incompatibilities, storage conditions and useful life-span, as well as, possibly, information relating to special properties of the object to which the system is to be stuck (label functions), preferably on the side which is averted from the adhesive side.
Also in the case of sheet-like adhesive systems such as medical plasters, that is, fixation plasters, wound plasters and, in particular, in the case of dermal/transdermal therapeutic systems comprising active agents, there is a need, and from case to case an indispensable requirement, to identifiably inscribe, and thereby to mark, such plasters according to their use, the kind of active ingredient, the spectrum of activities and side effects, the potential for intolerance, the allergy potential, the storage conditions, the expiry date, as well as according to information on the patients, etc.
With sheet-like systems such as adhesive systems containing active agents for plant protection there is also a need, and from case to case in indispensable requirement, to identifiably inscribe and thereby to mark such plasters according to the kind of active ingredient, their properties, the spectrum of activities and side effects, the potential for intolerances, the storage conditions, their expiry date, as well as according to information on the plants, etc.
The term “inscription” in the following will be understood as a synonym for any kind of identification, thus also including markings, symbols, bar cods, etc.
In the state of the art it is common practice to imprint and mark such adhesive systems employing, for example, a printing technique such as screen printing or tampon printing. This known technology does, however, have a number of disadvantages:                the printing ink requires time to dry,        printing ink adheres only for an insufficient duration to the polymer substrate provided for the purpose,        the pressure applied in the printing process may have a negative effect on the sheet-like adhesive system, the ingredients contained therein such as adhesives, additives such as softeners and enhancers, or on the active agent,        ink signs on the polymer substrate are easily blurred, especially upon contact with other materials,        most of the employable printing techniques can be carried out only intermittently, which reduces the rate of production,        because of the small working width of the printing techniques employed, the printing of the sheet-like adhesive system can not be performed on the broad webs of the adhesive films, but only after the systems have been separated.        
Furthermore, ink jet printers are known, to which in part the same disadvantages but also other disadvantages apply:                the printing ink requires time to dry,        printing ink adheres only for an insufficient duration to the polymer substrate provided for the purpose,        ink signs on the polymer substrate are easily blurred, especially upon contact with other materials,        the operating speed is low.        
It is also known to apply an inscription technique by means of a movably guided laser beam utilizing toners, wherein the toner is thermally fixed, for example, on paper; however, toner adheres only insufficiently to most polymer supports.
Furthermore, it is known to employ an inscription technique by means of a movably guided laser beam, for example, on a metal substrate, especially on a light metal substrate. Here, by way of punctually extremely intensive light emission, the laser beam produces temperatures so high that the crystal structure of the metal is superficially changed such that the metal adopts a different color. Laser beam appliances have also been used, for example, to apply letters or signs on electronic cables which are covered by a comparatively thick layer of plastic or rubber. Known are laser appliances for marking of cables with information by way of in-line laser marking which work with a freely programmable matrix system, this allows representation of almost any characters and symbols. Rates of up to 450 m/min are common in these lasers.
Owing to possible harmful effects of the laser beam on an inscription substrate of a thin polymer that is provided with ingredients such as adhesives, plasticizers, enhancers and active agents, and to the penetration depth of the beam, toner-free laser inscription on thin, sheet-like adhesive systems has heretofore not been made use of. With all adhesives there are fears that under the influence of high temperatures the adhesive mass will react with residual monomers, and with hot-melt adhesives it is feared that their adhesive power will be diminished under action of heat.